The present disclosure relates to a transmission apparatus, a transmission method, and a cable, and particularly to a transmission apparatus or the like that transmits content such as video and audio to an external apparatus through a cable.
Much of copyrighted content can be transmitted only for family use. In the past, transmission of content in wired connection such as IP transmission has been possible up to 100 m to meet the standards, and actually, it has been technically difficult to perform long-distance transmission of 100 m or more. Moreover, in wireless connection in which the connection mode is not visible and it is hard to limit the distance, there exists a method of achieving copyright protection by measuring a distance between apparatuses as round trip time (RTT) to estimate the distance and the number of repeaters, for example (see Japanese Patent Application Laid-open No. 2013-026686).
In recent years, an optical interface has been proposed as a technique to connect apparatuses to each other for achieving transmission of high-capacity data. This technique is expected to significantly improve the degradation of a transmission signal due to the long transmission distance as compared with the existing interface standards, and it may be possible to perform long-distance transmission of more than the distance limit. In this case, because the interface can perform high-capacity transmission at a high speed, it is technically very difficult to accurately measure the RTT. When such an interface technique is used to transmit copyrighted content, it may be impossible to limit the distance between the apparatuses to the distance corresponding to family use.